BALPA published a report last week that highlighted pilots’ abilities are compromised through fatigue. The organisation commissioned University College London to send questionnaires out to pilots working for a major British airline. 492 pilots (almost half) replied to the survey – 45% said they suffered “significant fatigue”.

One in five said their flying capabilities were compromised at least once a week because they hadn’t had enough sleep, and one pilot (working for a different airline) has now admitted to the BBC that he fell asleep after telling his co-pilot he could take a power nap, leaving the plane unmanned.

He said: “When I woke up, it was a big adrenaline rush. The first thing you do obviously is check your height and your speeds and all of your instrumentation.

“The worst scenario is that the autopilot would disconnect itself and then the aircraft would lose or gain height and that would be extremely dangerous as you’d go into the path of oncoming aircraft.

“Now there are warning systems that tell you you are deviating from the correct altitude but they are not excessively loud – it would be easy enough to sleep through that, and I probably don’t need to tell you what the consequences of that are.”

It is not known which airline the pilot works for or what route he was flying on during the incident.

The report has been published to highlight concerns that things will get worse as European authorities prepare to raise annual flying hours allowed from 900 to 1000. This, however, has been refuted by European officials.